全文获取类型
收费全文 | 3410篇 |
免费 | 224篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 163篇 |
妇产科学 | 67篇 |
基础医学 | 444篇 |
口腔科学 | 38篇 |
临床医学 | 717篇 |
内科学 | 535篇 |
皮肤病学 | 24篇 |
神经病学 | 307篇 |
特种医学 | 47篇 |
外科学 | 253篇 |
综合类 | 29篇 |
一般理论 | 3篇 |
预防医学 | 461篇 |
眼科学 | 36篇 |
药学 | 233篇 |
中国医学 | 3篇 |
肿瘤学 | 249篇 |
出版年
2022年 | 20篇 |
2021年 | 46篇 |
2020年 | 37篇 |
2019年 | 70篇 |
2018年 | 79篇 |
2017年 | 48篇 |
2016年 | 63篇 |
2015年 | 62篇 |
2014年 | 102篇 |
2013年 | 173篇 |
2012年 | 211篇 |
2011年 | 225篇 |
2010年 | 140篇 |
2009年 | 93篇 |
2008年 | 200篇 |
2007年 | 192篇 |
2006年 | 206篇 |
2005年 | 244篇 |
2004年 | 229篇 |
2003年 | 220篇 |
2002年 | 218篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 32篇 |
1998年 | 35篇 |
1997年 | 43篇 |
1996年 | 28篇 |
1995年 | 41篇 |
1994年 | 25篇 |
1993年 | 25篇 |
1992年 | 17篇 |
1991年 | 18篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1988年 | 20篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 20篇 |
1983年 | 24篇 |
1982年 | 23篇 |
1981年 | 42篇 |
1980年 | 23篇 |
1978年 | 19篇 |
1977年 | 21篇 |
1976年 | 19篇 |
1975年 | 14篇 |
1974年 | 17篇 |
1973年 | 14篇 |
1972年 | 16篇 |
1967年 | 11篇 |
排序方式: 共有3636条查询结果,搜索用时 26 毫秒
1.
Teenage pregnancy is a well-documented problem in the United States, with approximately 890,000 teenage pregnancies occurring each year. Although teen pregnancy rates have declined since 1991, rates remain higher than the mid-1970s and are fourfold those of European countries. Substantial morbidity and social problems result from these pregnancies, affecting the mother, her children, other family members, and society. Multiple educational approaches have been used, with few demonstrating significant reductions in teen pregnancy. School-based programs have been diverse and multifaceted. Recently, programs with a comprehensive approach have shown potential for success. In this article, characteristics and elements of promising school-based programs are identified and discussed. It is imperative that school nurses play an active role in developing and implementing prevention programs that incorporate rigorous evaluation. As health educators, school nurses are in a prime position to implement and evaluate the effectiveness of teen pregnancy prevention programs. 相似文献
2.
3.
4.
5.
6.
OBJECTIVES: This report presents final 2001 data on the 10 leading causes of death in the United States by age, race, sex, and Hispanic origin. Leading causes of infant, neonatal, and postneonatal death are also presented. This report supplements the annual report of final mortality statistics. METHODS: Data in this report are based on information from all death certificates filed in the 50 States and the District of Columbia in 2001. Causes of death classified by the International Classification of Diseases, Tenth Revision are ranked according to the number of deaths assigned to rankable causes. RESULTS: In 2001, the 10 leading causes of death were (in rank order) Diseases of heart; Malignant neoplasms; Cerebrovascular diseases; Chronic lower respiratory diseases; Accidents (unintentional injuries); Diabetes mellitus; Influenza and pneumonia; Alzheimer's disease; Nephritis, nephrotic syndrome and nephrosis; and Septicemia and accounted for nearly 80 percent of all deaths occurring in the United States. Differences in the rankings are evident by age, sex, race, and Hispanic origin. Leading causes of infant death for 2001 were (in rank order) Congenital malformations, deformations and chromosomal abnormalities; Disorders related to short gestation and low birth weight, not elsewhere classified; Sudden infant death syndrome; Newborn affected by maternal complications of pregnancy; Newborn affected by complications of placenta, cord and membranes; Respiratory distress of newborn; Accidents (unintentional injuries); Bacterial sepsis of newborn; Diseases of the circulatory system; and Intrauterine hypoxia and birth asphyxia. Important variation in the leading causes of infant death is noted for the neonatal and postneonatal periods. 相似文献
7.
Jane Maienschein James L. W. West Betty Bright 《Pediatric nephrology (Berlin, Germany)》2004,19(12):1437-1438
8.
Nearly a billion dollars were made available to state health departments through federal grants in the spring of 2002 for public health emergency preparedness plans. Twenty-one states had already been participating for some years in The Robert Wood Johnson Foundation's Turning Point Initiative. This article illustrates how earlier practice and experience in developing cross-sector collaborations and institutionalizing a model of broad-based partnerships for public health decision making can increase effectiveness and efficiency in responding to a call for action around an emergency. 相似文献
9.
10.
Bone marrow fat content in relation to bone remodeling and serum chemistry in intact and ovariectomized dogs 总被引:6,自引:0,他引:6
R. Bruce Martin Ph.D. Betty D. Chow Paul A. Lucas 《Calcified tissue international》1990,46(3):189-194
Summary It was previously shown that 11 months after ovariectomy the volume fraction of trabecular bone in the spine and 11th rib
medullary canal of Beagle dogs (6 control, 9 ovariectomized) was significantly reduced. In this paper it is shown that these
changes are accompanied by increased marrow fat volume in the 11th rib (59.0±9.5% vs. 44.3 ±10.0%). Conversely, the volume
fraction of functional (hematopoietic) cells in the marrow was reduced by ovariectomy. Additionally, variations in marrow
fat volume were tested for correlation with 22 other variables pertinent to bone physiology. Marrow fat volume was significantly
positively correlated with serum osteocalcin, rib trabecular bone porosity, rib cross-sectional area, and gains in body weight.
It was negatively correlated with serum estrogen concentrations and the extent of rib trabecular surfaces labeled with tetracycline. 相似文献